The present invention relates to a drive current limiting method in an electric power steering apparatus.
In a conventional electric power steering apparatus, a drive current to a motor for generating an auxiliary steering torque (to be simply referred to as a motor hereinafter) is monitored. If a drive current exceeding a predetermined value flows over a predetermined time period, an overcurrent countermeasure limits the current value (see Japanese Patent Laid-Open No. 1-197169).
When a steering wheel is locked, for example, this countermeasure limits an excessive drive current to a motor and in this manner prevents damage from a fire caused by a temperature rise in the motor or protects a battery.
Such a conventional current limiting method, however, limits the current value of an excessive drive current flowing when a steering wheel is abruptly turned. As a result, a force required to turn the steering wheel is suddenly increased to cause unsmoothness in a steering operation.